It has been recognised that there is a need to provide accurate information to a user of a dispensing apparatus, such as a pressurised metered dose inhaler, concerning the quantity of doses delivered from, or remaining in, the dispensing apparatus. Without such information, there is a danger that a user may be unaware that the dispensing container of the dispensing apparatus is empty or close to empty. This is especially dangerous where the dispensing apparatus is for use in delivering medicinal compounds for the treatment of chronic or acute symptoms, for example, as in the case of a pressurised metered dose inhaler used for treating asthmatic reactions.
It is known to provide a dispensing apparatus with a dose indicator device. Typically such dose indicator devices are triggered by movement of the dispensing container wherein the movement either directly or indirectly provides the motive force for incrementing or decrementing the dose indicator device. EP1758631 disclose one example of a dose indicator device. This device, while accurate and robust, comprises a relatively large number of separate components.
It would be desirable to produce a dose indicator device that requires fewer components.